ASTRO: DSLR trickery - 2 attachments

Thought I'd give an idea a try. My scope is an old Meade 6" Newt
all manual. I do have a Nikon D200, which I piggybacked to the
scope set at wide field 35mm equivalent of 42mm.

To track, I was zoomed in 200x on a guide star and manually turned
knobs during exposure.

But here's the trick. Without a remote the camera is limited to
30 second exposures. However...... The camera has the ability to
do multiple exposures on the same frame. So what I did was set
the camera to take those multiple exposures and used the interval
timer function to take them automatically.

It's like stacking, but it was all done within the camera!

Nifty, eh?

One pic is of the Milky Way through Cygnus. This is five 30 second
exposure.

The other is of the field around M31 and M33, which is 10 exposures.
I knew I'd get M31 but was surprised to get M33 as well.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?

That brings back memories - from late seventies into the early
ninities, I spent many a night manually guiding while doing film.

When gas-hypering became available, I switched to Tech Pan and learned
how to develope and print the images. Still have prints on my office
walls - they pale in comparison with the ccd images but I still enjoy
looking at them.

They most closely relpicate what one would see through a moderate size
scope so are useful when doing presentation - too many people think
they will see all those beatiful colors when they look through a
scope.

On Fri, 10 Sep 2010 06:02:28 GMT, Skywise
wrote:

Thought I'd give an idea a try. My scope is an old Meade 6" Newt
all manual. I do have a Nikon D200, which I piggybacked to the
scope set at wide field 35mm equivalent of 42mm.

To track, I was zoomed in 200x on a guide star and manually turned
knobs during exposure.

But here's the trick. Without a remote the camera is limited to
30 second exposures. However...... The camera has the ability to
do multiple exposures on the same frame. So what I did was set
the camera to take those multiple exposures and used the interval
timer function to take them automatically.

It's like stacking, but it was all done within the camera!

Nifty, eh?

One pic is of the Milky Way through Cygnus. This is five 30 second
exposure.

The other is of the field around M31 and M33, which is 10 exposures.
I knew I'd get M31 but was surprised to get M33 as well.

Brian

glen youman wrote in
:

They most closely relpicate what one would see through a moderate size
scope so are useful when doing presentation - too many people think
they will see all those beatiful colors when they look through a
scope.

Yep. I only recently moved to a relatively dark sky. Course, just
about anything is dark compared to Los Angeles. It's nice to be able
to see M31 naked eye. I was surprised as heck to suddenly notice
the Pleiades popping up on the horizon last night.

I've tried in the past to see M33 in the scope but could never find
it for some reason. Looks like I made myself a perfect finder chart!

BTW, I did process the images as I still had some light pollution.
I made a pseudo-dark to do that and did some contrast/brightness.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?

Your multi exposure method is probably preferable to stacking as each
time you read out an image it adds read noise. Reading once would
result in less noise by the square root of the exposures stored rather
than read out. Images came out well.

I got my start in deep sky imaging back in the 50's using a barn door
tracker. First one hinge then two hinge. At first I sat there and
turned a screw one rotation every 15 seconds watching a large glow in
the dark alarm clock (wind up). I coated the second hand with
radioactive paint so it glowed continuously without need for recharging
it with a flashlight. Then when I built the two hinge model I figured
out a way to use the spring and gears along with an extra gear to turn
the drive screw which now was one rpm not 4. So I now had a clock
drive! Worked well for 10 minute film images (before hypering) using
either Tri-X pushed to ASA 1200 or High Speed Extachrome ASA 160 pushed
to 320. I developed both. It worked well up to 135mm lenses. Then
figured a way to guide it using a 40mm scope of unknown power (about 25
I think). I hoped it would work with my 400mm lens and did for one 30
minute shot of M31. But mainly used for longer exposures with the
shorter lenses.

Later by the late 50's I had a 10" Cave f/5 for imaging. Horrid periodic
error. I had to stay glued to the guiding eyepiece (now a 60mm
refractor at 120x). Used a inverter to get the AC needed. Backlash in
dec motor was severe so had to be sure to be just enough off the pole
dec corrections went in only one direction but close enough that
rotation wasn't an issue.

Those were the "fun" years. Did it the hard way for 50 years.

Now it is so easy it is criminal. I program a night into the computer
and it runs up to 12 hours in winter without me! I'm yet to automate
closing down due to clouds so sometimes get wakened by the cloud sensor
going off. Other times clouds aren't thick enough to set it off but do
ruin images. Since I normally don't guide (thanks to the

Now if I could just get it to do the processing as well!

Rick

On 9/10/2010 1:02 AM, Skywise wrote:
Thought I'd give an idea a try. My scope is an old Meade 6" Newt
all manual. I do have a Nikon D200, which I piggybacked to the
scope set at wide field 35mm equivalent of 42mm.

To track, I was zoomed in 200x on a guide star and manually turned
knobs during exposure.

But here's the trick. Without a remote the camera is limited to
30 second exposures. However...... The camera has the ability to
do multiple exposures on the same frame. So what I did was set
the camera to take those multiple exposures and used the interval
timer function to take them automatically.

It's like stacking, but it was all done within the camera!

Nifty, eh?

One pic is of the Milky Way through Cygnus. This is five 30 second
exposure.

The other is of the field around M31 and M33, which is 10 exposures.
I knew I'd get M31 but was surprised to get M33 as well.

Brian